Greater Flexibility in Clock Oscillators for Enhanced by SiTime


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									Greater Flexibility in Clock Oscillators for Enhanced

A crystal oscillator is an electronic circuit that is used for creating electrical signals of an accurate frequency. These
frequencies are required for providing stable clock signals in digital integrated circuits and also for the purpose of
stabilizing frequencies for radio transmitters and receivers. Quartz crystals are manufactured for developing resonators
that are used commonly in wristwatches, clocks, radios, computers and cell phones. They are also used in test and
measurement and medical equipment.

Despite being a popular item in electronic systems, the crystal oscillator does not have the capacity for high frequency
resonance. Using the crystal quarts oscillator above its normal frequency can raise costs and there is no guarantee of a
stable temperature range. The only way to increase the frequency level is by using phase locked loops. However, the
crystal oscillator is not proficient in analog circuits. As the need for enhanced performance and reduced costs are
increasing, an alternative has been found in the form of programmable clock oscillators that use a fixed frequency
MEMS resonator along with a programmable analog circuit.

The MEMS clock oscillator utilizes an extremely accurate fractional-n phase locked loop to multiply the MEMS resonator
and achieve any frequency. The accuracy of the output frequency is up to 6 decimal places and is ideal for applications
that require non-standard frequencies and/or higher frequencies. This results in improved accuracy and jitter
performance due to less ASIC or SoC PLL multiplication. The clock oscillator can easily operate in any supply voltage from
2.5V to 3.3V and as low as 1.8V.

MEMS-based clock oscillators provide programming controls including the ability to program different drive strengths to
better match output conditions.. In addition, higher drive strength can be used for driving multiple loads. Similarly, the
lower drive strength can be used for reducing the electromagnetic interference. Programmability also allows the clock
oscillator to feature a pin that can be configured for either Output Enable or Standby. And unlike quartz-crystal
oscillators, the pull range of a MEMS VCXO can extend to +/-1600 PPM. This unique pull-range enables new
applications that were previously unobtainable due to the limited pull-range of any quartz-based oscillator; typically only
150-200 PPM max.

Learn more about : MEMS Oscillators & TCXO

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